<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style>
    /* 
    .parent>p{} 亲儿子
    */
    /* 
      .parent>p{
       color:red;}
    */
    /* .parent p{} 选择parent之后的所有p元素  */
    .parent p{
        color: red;
    }
    </style>
</head>
<body>
    <div class="parent">
        <p>hello world</p>
        <p>hello world</p>
     <div>
        <p>hello world</p>
     </div>
    </div>
  <div>
      <p>hello world</p>
  </div>
</body>
</html>